In general, gas turbine engines combust a fuel-air mixture to form a high temperature combustion gas stream. The high temperature combustion gas stream is channeled to a turbine via a hot gas path. The turbine converts the thermal energy from the high temperature combustion gas stream to mechanical energy so as to rotate a turbine shaft. The gas turbine engine may be used in a variety of applications, such as for providing power to a pump or an electrical generator and the like.
Operational efficiency generally increases as the temperature of the combustion gas stream increases. Higher gas stream temperatures, however, may produce higher levels of nitrogen oxide (NOx), an emission that is subject to both federal and state regulation in the U.S. and subject to similar types of regulation abroad. A balance thus exists between operating the gas turbine in an efficient temperature range while also ensuring that the output of NOx and other types of emissions remain below the mandated levels.
The fuel-air mixture may be combusted in a combustor via a number of mini-tube bundle nozzles. These mini-tube bundle nozzles or other types of combustion nozzles may be utilized so as to reduce emissions and also to permit the use of highly reactive types of syngas and other fuels.
High hydrogen fuel combustion, however, may excite frequencies higher than about a kilohertz or more as well as longitudinal acoustic modes in combustors configured with the mini-tube bundle nozzles or other types of combustion nozzles. The screech and other types of combustion dynamics may occur through the combustion interaction between adjacent nozzles and the coupling of the combustion processes and geometry. The combustion dynamics may cause mechanical fatigue even at low amplitude and may lead to hardware damage at higher amplitudes.
There is a therefore for a desire for an improved combustor that avoids or at least mitigates against advanced combustion dynamics. Such a combustor should avoid such combustion dynamics while maintaining highly efficient operation with minimal emissions.